Washington State University researchers have attempted to find a solution to the problem of fly ash, a waste product of coal-based electricity generation and a known environmental and waste management issue. Xianming Shi, associate professor in WSU's Department of Civil and Environmental Engineering, and graduate student Gang Xu, have used graphene in their new method that makes use of fly ash for the production of concrete.
The durable new concrete eliminates the use of cement, which is known to be harmful to the environment. Instead of cement, the fly ash is used as a binder in the concrete. By doing this, Shi and Xu are able to tackle two environmental issues with one solution.
Traditionally, concrete is processed by mixing cement with sand and gravel, which contributes anywhere from five to eight percent of greenhouse gas emissions worldwide. Cement is the key ingredient in concrete and to produce it requires extremely high temperatures and a massive amount of energy.
Some researchers have attempted to use fly ash in concrete production but haven't been able to eliminate the intense heating step involved in creating cement. "Our production method does not require heating or the use of any cement," said Xu.
In order to activate the fly and turn it into a cement-like material capable of binding the concrete, the team used graphene oxide and combined it with the fly ash and water. The combination creates a chemical reaction which rearranges the atoms in the solution, creating strongly bonded atoms in a durable, cement-like binder.
Shi and Xu designed the fly ash concrete to be pervious, meaning that water is able to pass through it. This has the benefit of replenishing groundwater as well as lower potential for flooding.
Several tests at the WSU campus have shown that the new concrete can withstand various kinds of weight loads and temperatures. Other tests, like monitoring sensors buried under the concrete, are still underway.
The researchers hope to one day commercialize the patented technology. "After further testing, we would like to build some structures with this concrete to serve as a proof of concept," said Xu.
The graphene-enhanced concrete field seems to be a booming one and several projects are taking place. In June 2018, Australia-based advanced materials company Talga Resources reported high levels of electrical conductivity in concrete by using an additive developed from the Company’s graphene-graphite research and development laboratory in the UK. In April 2018, researchers from the University of Exeter developed a new technique that incorporates graphene into traditional concrete production, to make more than twice as strong and four times more water resistant than existing concretes. In May 2017, Zenyatta Ventures announced that the next phase to test a graphene-enhanced concrete admixture is progressing through their Collaboration Agreement with Larisplast, an Israeli business that specializes in the field of concrete admixtures.